The effects of initial concentrations of PNP, doses of TiO2, cations and anions have been investigated to find out the conditions for the maximum degradation of PNP in presence of 254 nm UV light. The rate of photocatalytic degradation of PNP was increased with increasing TiO2 dose until the dose concentration reached at a value 0.4 g/100 mL. Further increase of TiO2 decreased the degradation. The maximum degradation of PNP was found with the catalyst dose 0.4 g/100 mL at pH 3. The degradation of PNP was decreased with increasing of PNP concentration. About 90% degradation of PNP was observed when 1.0 × 10﹣4 M PNP was irradiated for 2 hours in 0.4 g/100 mL of TiO2 suspension. The effect of Cu(II) and Fe(II) ions on the degradation was also investigated. Addition of Cu(II) ions enhances the percent degradation but excess of Cu(II) ions decreases the degradation. Under the same experimental conditions, the presence of and is found to be detrimental to the photodegradation of PNP. Hydrogen ion concentration of reaction mixture was found to increase continuously during photodegradation suggesting mineralization of PNP.
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